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Title: Development of silver catalysts for the heterocyclization reactions of alakynes
Author: Wong, Hui Lin Valerie
ISNI:       0000 0004 5367 4666
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2015
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This PhD thesis describes work undertaken to develop efficient silver(I) catalysts for the intramolecular reactions of alkynes with nitrogen and oxygen containing nucleophiles for the synthesis of heterocycles. The introductory chapter provides an overview of recent advances in silver-catalyzed heterofunctionalization reactions of alkynes, with a focus on reactions involving C-N and C-O bond formations. A summary of the catalytic applicat ions of silver(I) NHC catalysts in the literature, which will be explored in Chapter 4, is also provided. Chapter 2 begins with the screening of silver salts as catalysts for the intramolecular hydroamination of alkynes with trichloroacetimidates. A strong counteranion effect on selectivity was observed. The impact of employing silver(I) complexes with variety of P- and N- donor ligands on catalytic activity was also explored, where pyridine-ligated silve r salts showed superior activity and selectivity. Reaction optimization was undertaken, and 1-bromoalkyne substrates were effectively cyclized with catalytic loadings as low as 1 mol%. Chapter 3, the application of the pyridine-ligated silver salts developed in Chapter 2 as catalysts for the cycloisomerization of propargyl amides is described. A broader substrate scope was observed compared to the previously reported AgSbF6 catalyst and a mechanism for the reaction is proposed based on experimental observations. In Chapter 4, the synthesis and characterization of a new class of silver(I) NHC carboxylate complexes are presented. The activity towards the cycloisomerization of propargyl amides was investigated, and they showed complementary reactivities compared to the pyridine-ligated silver catalysts in Chapter 3. In Chapter 5, an overall conclusion and future work are discussed. The last Chapter contains experimental procedures and characterization data of all the compounds synthesized during the course of this project.
Supervisor: Hii, King Kuok (Mimi) Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral